The present invention relates to semiconductor devices, particularly transistors, and a method for making the transistors. More specifically, it relates to improvements in a carrier mobility.
It has hitherto been known that transistors include MOSFETs and bipolar (BIP) transistors.
Regarding the MOSFETs, a carrier mobility has been improved by establishing a state in which a tensile strain is exerted on a semiconductor film overlying an insulator. As an example of such improvements, reference is had to "STRESS-ENHANCED MOBILITY IN MOSFETs FABRICATED IN ZONE-MELTING-RECRYSTALLIZED POLY-Si FILMS" reported by B. Y. Tsaur, Johnn C. C. Fan, M. W. Geis, D. J. Silversmith and R. W. Mountain in 'Technical Digest of IEDM (1981)', pp. 232-242, Dec. 1981.
However, there have not been known yet a construction which can improve carrier mobilities when applied to both the MOSFETs and the bipolar transistors, and a method for making the same.